title: Oncogenicity of L-type amino-acid transporter 1 (LAT1) revealed by targeted gene disruption in chicken DT40 cells: LAT1 is a promising molecular target for human cancer therapy.
abstract: L-type amino-acid transporter 1 (LAT1) is the first identified light chain of CD98 molecule, disulfide-linked to a heavy chain of CD98. Following cDNA cloning of chicken full-length LAT1, we have constructed targeting vectors for the disruption of chicken LAT1 gene from genomic DNA of chicken LAT1 consisting of 5.4kb. We established five homozygous LAT1-disrupted (LAT1(-/-)) cell clones, derived from a heterozygous LAT1(+/-) clone of DT40 chicken B cell line. Reactivity of anti-chicken CD98hc monoclonal antibody (mAb) with LAT1(-/-) DT40 cells was markedly decreased compared with that of wild-type DT40 cells. All LAT1(-/-) cells were deficient in L-type amino-acid transporting activity, although alternative-splice variant but not full-length mRNA of LAT1 was detected in these cells. LAT1(-/-) DT40 clones showed outstandingly slow growth in liquid culture and decreased colony-formation capacity in soft agar compared with wild-type DT40 cells. Cell-cycle analyses indicated that LAT1(-/-) DT40 clones have prolonged cell-cycle phases compared with wild-type or LAT1(+/-) DT40 cells. Knockdown of human LAT1 by small interfering RNAs resulted in marked in vitro cell-growth inhibition of human cancer cells, and in vivo tumor growth of HeLa cells in athymic mice was significantly inhibited by anti-human LAT1 mAb. All these results indicate essential roles of LAT1 in the cell proliferation and occurrence of malignant phenotypes and that LAT1 is a promising candidate as a molecular target of human cancer therapy.
authors.affiliation: Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Ohkawa
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Ohno
authors.forename: Kazue
authors.initials: K
authors.lastname: Masuko
authors.forename: Akiko
authors.initials: A
authors.lastname: Takeuchi
authors.forename: Kentaro
authors.initials: K
authors.lastname: Suda
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kubo
authors.forename: Rieko
authors.initials: R
authors.lastname: Kawahara
authors.forename: Shogo
authors.initials: S
authors.lastname: Okazaki
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Tanaka
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saya
authors.forename: Masayuki
authors.initials: M
authors.lastname: Seki
authors.forename: Takemi
authors.initials: T
authors.lastname: Enomoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Yagi
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Masuko
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002645:Chickens; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D027283:Large Neutral Amino Acid-Transporter 1 / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000235:genetics* / Q000628:therapy*; D034622:RNA Interference
chemical_list: D000911:Antibodies, Monoclonal; D027283:Large Neutral Amino Acid-Transporter 1